About Seven Fifty cafe & Zephyr rear brakes.

This post is about rear brakes for my Seven Fifty cafe-racer project. But as Zephyr 750 swingarm used in this project, this article may  be also useful for those Zephyr owners, who decided to refresh rear brakes on their bikes.

The question of front Zephyr brake units replacement is quite simple. There are a lot fresh Kawasaki, like ER-6 or Z750 from which calipers and master cylinder could be taken and simply mounted instead of old Zephyr ones.  But the question of rear brakes is more complicated because of eccentric chain adjusting system.

That’s how Zephyr 750 stock rear brake looks:

After more than two decades  of exploitation it usually has ugly look and its work is far from perfect (even if caliper was rebuilt)…

And a couple of years ago I invented  how Zephyr rear brakes may be as not upgraded, but at least well refreshed. Theoretically solution for this question may be based on ZX11, ZRX1100 or ZRX1200 braking components but (without mention of other features) Zephyr has mounting for caliper torque rod above swingarm, while ZX and ZRX  below swingarm, so I decided to find more easy way.

And that’s how rear brake system on my Zephyr looks after upgrade:

Now I repeated this solution in case of Seven Fifty cafe-racer project, so I shot photos for  illustration and thus have a good reason to write  this article.

So what do we need?

First thing is ZZR600 1993-1999 rear brake caliper holder.  On this photo upper unit is ZZR holder and lower unit is Zephyr 750 holder.

As you can see there is need of axle hole  drilling or machine milling. The point of this process is right positioning of holder to avoid skew.  After milling original Zephyr holder bushing could be pressed in its place:

And part is ready for use:

In case of Seven Fifty I designed and ordered  custom collar for caliper holder but in case of Zephyr original collar  still may be used.

Second lot we need is rear brake system itself.  The one from fresh years Kawasaki ER-6 or Z750 fits perfectly  to both ZZR600 caliper holder  and Zephyr master cylinder mounting points. In case of Seven Fifty there is need of modifying master cylinder mount .

And last thing in our list is 240mm rear brake rotor. There are plenty of ZZR600 discs on ebay and they fit to Zephyr rear wheel  like original 220mm one.  In case of Seven Fifty I had only to replace  worn out  rotor with  new one because Cb750 brake disc diameter is exactly 240mm.

After all parts are gathered we could montage the system. Wheel is installed and rear caliper holder could freely rotate around collar.

Holder on its working  position:

And  with caliper installed:

The advantages of such modification is obvious:

•  All brake components are fresh and calipers have modern coating, so there is no need in any painting, rebuilding and pistons/rubbers changing. Only light cleaning and guides regreasing.
• New one piston caliper with 240mm brake rotor works better than old two pistons  caliper with 220mm disc.

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